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Sen AP, Meiselbach MK, Anderson KE, Miller BJ, Polsky D. Physician Network Breadth and Plan Quality Ratings in Medicare Advantage. JAMA Health Forum. 2021;2(7):e211816. doi:10.1001/jamahealthforum.2021.1816
Nearly 40% of beneficiaries elect to access their Medicare benefits through Medicare Advantage (MA), in which capitated private health insurers construct physician and hospital networks and a benefits package with a minimum of Medicare Parts A and B benefits. Most plans also integrate prescription drug coverage (Part D). In exchange for network and utilization controls, beneficiaries typically receive supplemental benefits and an annual cap on out-of-pocket expenses. Medicare Advantage insurers receive a quality bonus that is tied to a star rating of 4 or greater on a 5-star scale.
If MA insurers use networks to manage costs, enrollees may face tradeoffs between cost and quality. Narrow networks may direct enrollees to cost-effective, high-quality hospitals and physicians or limit access to necessary high-cost, high-quality care. While we know network breadth varies across MA plans1-3 and may be associated with plan quality,4 in this study, we explored the extent of narrow networks across MA, types of counties where they are common, enrollment in narrow network plans, and how networks are associated with star ratings.
We used Vericred physician networks data, publicly available US Centers for Medicare & Medicaid Services MA plan data, and Census and Area Health Resources File data on county characteristics. We examined the 2019 physician network breadth among the most prevalent MA plan designs (health maintenance organizations and preferred provider organizations), described the percentage of enrollees in narrow network plans by state, and assessed whether network breadth was associated with star ratings, adjusting for plan and county characteristics. Star ratings were calculated as a weighted average of clinical, process, and outcome measures and ranged from 1 to 5 in 0.5 increments.
We defined network breadth as the percentage of eligible county-level physicians in network, with narrow defined as fewer than 25% of eligible physicians. All results were weighted by plan-county enrollment. Details of data and sample construction are in the eMethods in the Supplement. Our study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines. Statistical analyses were performed in Stata, version 17 (StataCorp) and R, version 3.6.1 (R Foundation for Statistical Computing). Statistical significance was set at a 95% confidence level. The Johns Hopkins University institutional review board exempted this study from review because no patient data were used and all data were publicly accessible.
Our analytic sample included 44 715 plan-counties and 18 488 434 MA enrollees (82%). The mean (SD) MA network included 41.2% (27.8%) of local physicians (Table 1). Of 44 715 plan-counties, 12 552 (28%) had narrow networks and 32 163 (72%) had non-narrow networks. Among narrow network plans, 79.8% were health maintenance organizations compared with 50.7% among non-narrow plans. More narrow networks were in large metropolitan counties (40.0%) than non-narrow networks (26.7%). The mean MA penetration and mean percentage of population older than 65 years who was self-identified as Hispanic were higher in counties with narrow networks. Overall, 31% of enrolled beneficiaries were in narrow network plans. Six states had more than 50% of beneficiaries in a narrow network plan (California, Florida, Minnesota, Maryland, Wyoming, and Kansas).
The mean (SD) star rating for narrow network plans was 4.12 (0.49) compared with 3.75 (0.4) among plans with non-narrow networks (Table 2). Among narrow networks, 51.5% were associated with plans with 4.5 or more stars compared with 9.2% among non-narrow plans. In models that adjusted for plan type and county characteristics, narrow networks were associated with 0.21 more stars than non-narrow networks. Results were significant, although smaller in magnitude, with the exclusion of Kaiser plans.
Narrow physician networks were positively associated with star ratings. Plans may use narrow networks to achieve a higher star rating by selectively contracting with physicians and/or actively managing the quality of physicians in their network. Potential network data inaccuracies limit this study. Further, we did not investigate characteristics of narrow networks (eg, physician specialty), hospital networks, or whether high-star, narrow network plans serve beneficiaries well. Star ratings may reflect a higher quality of care; however, the evidence is mixed.5,6 Future work to identify the mechanisms that contribute to the positive association between narrow networks and star ratings, and implications for beneficiaries, will be important for Medicare policy.
Accepted for Publication: June 3, 2021.
Published: July 30, 2021. doi:10.1001/jamahealthforum.2021.1816
Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2021 Sen AP et al. JAMA Health Forum.
Corresponding Author: Aditi P. Sen, PhD, 624 N Broadway, Baltimore, MD 21205 (firstname.lastname@example.org).
Author Contributions: Dr Sen and Mr Meiselbach had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: All authors.
Acquisition, analysis, or interpretation of data: Sen, Meiselbach, Anderson, Miller.
Drafting of the manuscript: Sen, Meiselbach.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Sen, Meiselbach.
Supervision: Sen, Miller, Polsky.
Conflict of Interest Disclosures: Dr Sen reported grants from Arnold Ventures outside the submitted work. Dr Anderson reported being a former employee of the Lewin Group outside the submitted work. Dr Miller reported being a member of the US Centers for Medicare & Medicaid Services (CMS) Medicare Evidence Development and Coverage advisory committee as well as personal fees from the US Federal Trade Commission, US Health Resources and Services Administration, Oxidien Pharmaceuticals, Heritage Foundation, and Raydus Research outside the submitted work. Dr Polsky reported personal fees from Extend Health outside the submitted work. No other disclosures were reported.
Funding/Support: This study was partially funded by Agency for Healthcare Research and Quality grants R01 HS025976-01 and T32HS000029.
Role of the Funder/Sponsor: The funding organizations had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Disclaimer: The content is solely the responsibility of the authors and does not necessarily represent the official views of the Agency for Healthcare Research and Quality. Dr Miller’s views are his own and do not represent those of the CMS.
Additional Contributions: We thank Matthew V. Zahn, MA, Johns Hopkins University, for assisting with acquisition and interpretation of MA premiums data. He was not compensated for his contributions.